Why some section properties are missing and other is so different?

The composite section is made of steel and concrete, it has three parts: thin-walled steel section , bottom concrete (red) and top concrete (green)

I define two IDENTICAL composite sections, the difference between them is the way I define the steel section.

  1. For the 1st section, I use explict coordinates as below to define the steel section.
POLY TYPE MNO
O 1
VERT NO Y Z
101 0.0000 1.2000
102 0.0405 1.1984
103 0.0808 1.1934

The composite section properties are below


The section properties of 3 parts are below, 1 is steel section, 11 is bottom concrete and 12 is top concrete.

  1. For the 2nd section, I use “TVAR” and formulars as below to define the steel section.
POLY TYPE MNO $ 拱肋外圈
OPZ 1
VERT NO Y Z TYPE R REFP
101 0 ‘=-#H/2’ O
102 ‘=#D/2’ 0 TP ‘=#D/2’ 101
103 ‘=#D/2’ ‘=-#H/2+#D/2’ O

The composite section properties are below


The section properties of 3 parts are below, 1 is steel section, 11 is bottom concrete and 12 is top concrete.

  1. As for top and bottom concrete sections, I use the “CIRC” as below for both sections
CS 400
CIRC NO Y Z R MNO
1 0 ‘=(#H-#D)/2’ ‘=#D/2-#TF 11
CS 500
CIRC NO Y Z R MNO
2 0 ‘=-(#H-#D)/2’ ‘=#D/2-#TF 12

From the above section properties, you can find that the area and moment of inertia are very close,
BUT

  1. Since the approach to define the concrete section is the same for both sections, why the shear areas (Ay, Az) and torsion moment of inertia (It) for top (Material 12) and bottom (Material 12) concrete section are zeroes in the 2nd section?
  2. Why the shear areas of steel section in the 2nd section is zero?
  3. The It values of steel section (Material 1) in the1st and 2nd sections are so different, 3.357E-2 vs. 2.927E-1

There is no geometry related error or warning in the 2nd section analysis, the only wanring is related to material

SOFiSTiK 2022-2.0.558 AQUA - GENERAL SECTIONS
Output on file Aqua - Arch.plb
Project data base Aqua - Arch.cdb - 10. access
+++++ warning no. 12286 in program SOF_INP_MSTEEL ; input line: 11
Material 2 has a class which is not known in the tables of the program
This is allowed for historical or damaged materials, but an explicit
definition of the intended strength values is then strongly recommended!
TIME NEEDED 3, TOTAL 3
DATE 2022-02-13, 15:34:17

WHY?

I ran the analysis more than 10 times for the 2nd section, and i always got section properties with shear areas = 0.

When I ran analysis a few minites ago, it shows all the section properties.


comared to the previous results

  1. The shear area are not zero
  2. the It (3.453E-2) of steel section is similar to that of the 1st section (It = 3.357E-2), while the previous It (2.927E-2) is much bigger.